Three?Dimensional, Time?Resolved Motion of the Coronary Arteries

Abstract

A period lasting an average of 187 msec was seen during mid-diastole (72+/-5% of the cardiac cycle) in which all three coronary arteries studied had relatively little motion. This period of quiescence was consistent along the length of the arteries. Although the amount of motion did vary along the length of the arteries, there was no difference in the timing of rest periods in the proximal, mid, and distal segments using a < 1 mm per frame threshold. The periods of low motion were significantly reduced in length and often altogether eliminated when the 0.5 mm per frame threshold was used.

Correction for heart rate variability during 3D whole heart MR coronary angiography

“…In accordance with most previous studies, data were acquired in diastole, typically the most quiescent period in the cardiac cycle (4,17,25). However, a more recent study suggests that imaging at end-systole does not affect image quality if the acquisition window is SENSE abbreviated (34).…”

“…The most quiescent period of the cardiac cycle is typically found in mid-diastole. Its duration has an inverse relationship with the heart rate: it shortens when the heart rate increases (17). Therefore, the position (and duration) of the cardiac rest period within the cardiac cycle is affected by heart rate variability.…”

“…[6] the constant Tm 0 refers to the time delay between the R-wave of the ECG and the onset of the diastolic period of minimal coronary motion of the right coronary artery (RCA) as was visually determined on high temporal resolution cine images in a horizontal long-axis view that precede 3D whole-heart coronary MRA. Although the three major coronary arteries each have different motion patterns and only partly overlapping rest periods, the middle segment of the RCA was analyzed, since in previous studies the most significant coronary artery displacement was observed in this coronary segment, and this segment also appeared to have the shortest period of minimal motion (17). Importantly, this time period overlaps with the moment of minimal motion of the proximal, middle, and distal segments of all three major coronary arteries (17).…”

“…Although the three major coronary arteries each have different motion patterns and only partly overlapping rest periods, the middle segment of the RCA was analyzed, since in previous studies the most significant coronary artery displacement was observed in this coronary segment, and this segment also appeared to have the shortest period of minimal motion (17). Importantly, this time period overlaps with the moment of minimal motion of the proximal, middle, and distal segments of all three major coronary arteries (17). Therefore, we hypothesized that by identifying Tm 0 of the RCA at a mid-ventricular level, an adequate timepoint for minimizing coronary motion in general was utilized.…”

Cardiovascular Magnetic Resonance

“…114 Invasive coronary angiography has higher spatiotemporal resolution and currently is the only means to place coronary stents. A number of special CMR techniques are used to mitigate the problems: Imaging is performed when diastole limits cardiac motion; a 3D volume captures tortuous vessels; respiratory gating with navigator echoes reduces breathing-induced blurring; parallel imaging accelerates acquisition; and contrast agent or prepulses improve coronaryto-background contrast.…”